1. Technical Field
The present invention relates to a display apparatus including a light source, a light guide plate or diffusion plate, an optical sheet and a display panel.
2. Description of Related Art
A thin television receiver such as a liquid-crystal television receiver (hereinafter referred to as TV receiver) generally has a display module (display apparatus: liquid-crystal display module in the case of a liquid-crystal TV receiver), and a substrate for driving the display module. The display module is accommodated vertically in a front cabinet and a rear cabinet that are vertically arranged at the front and back sides. In the case of being a liquid-crystal display module of an edge light type, the display module includes, for example, a display panel and a backlight unit having, an optical sheet, a light guide plate, a reflection sheet and a chassis. A light source such as an LED substrate in the backlight unit is disposed at a side plate of the chassis. In the displaying operation, planar light is emitted from the light guide plate, and the back surface of the display panel is illuminated with the light.
The display panel has a liquid-crystal layer, a pair of glass substrates (a color filter substrate, a TFT substrate) and polarization plates. The pair of glass substrates are bonded to each other through a seal material, and hold the liquid-crystal layer between them. Each polarization plate is placed on a surface at the opposite side from the liquid-crystal layer side of each of the pair of glass substrates.
The optical sheet is configured to perform light control such as light reflection, polarization, refraction and diffusion in order to improve the quality of an image, i.e. to increase the luminance, to make the surface luminance uniform and the like, on a screen of the display panel.
In the case where the optical sheet is not positioned by the display module, it may flap and make contact with the polarization plate or the like, possibly causing a flaw.
Moreover, in the case where the optical sheet is positioned by hanging it at the middle of its upper side, the load is concentrated at the hanging portion of the sheet. Since the sheet's own weight has become heavier along with the increased size of the display module, the sheet may easily deflect, which causes such a problem that a slit is generated at the hanging portion due to vibration or impact. Also when the optical sheet is so configured that: a protrusion of an angled plate-like shape protruding upward is formed at the upper side part of the optical sheet; a latch hole is formed at the protrusion; a projection is further formed at a part of the light guide plate opposed to the latch hole: and the optical sheet hangs while the projection is inserted into the latch hole, the protrusion may be torn.
An example of a display apparatus so configured that the middle part of the upper side of the optical sheet is used to hang the optical sheet as described above is disclosed in Japanese Patent Application Laid-Open Publication No. 2007-24913, which prevents the image quality from degrading by a part of components of optical sheets, which is separated due to mutual friction between the optical sheets caused by vibration or impact during transportation of the display apparatus and which generates fine powder-like dust remaining in a light path or moving to an unspecified portion of the light path.
FIG. 15 is a partial vertical section view illustrating a display apparatus according to Japanese Patent Application Laid-Open Publication No. 2007-24913.
The display apparatus comprises a display panel 21, an optical sheet group 22 including, for example, three optical sheets, a chassis 24, a panel holding member 26, a bezel 27, a reflection member (diffusion plate) 36 and a front cabinet 37.
The chassis 24 has a substantially box-like shape with the display panel 21 side being open, and has an opening edge protruding outward. Moreover, at the middle part in the lateral direction of the display panel 21 on the upper side part of the chassis 24, a projecting part 245 protruding toward the display panel 21 side is formed.
The reflection member 36 also has a substantially box-like shape and is so formed that the bottom part thereof is in contact with the bottom part of the chassis 24 and the side part thereof is formed to rise obliquely upward, and that the opening edge protruding outward is in contact with the opening edge of the chassis 24 through a buffer member 246.
At the middle part in the lateral direction of the upper side of the optical sheet group 22, a latch hole 228 is formed.
While the projecting part 245 is inserted into the latch hole 228, the optical sheet group 22, reflection member 36 and buffer member 246 are held between a frame-shaped panel holding member 26 and the opening edge of the chassis 24.
An upper edge of the display panel 21 is held between a frame-shaped bezel 27 and the panel holding member 26.
According to the configuration described above, the display panel 21, optical sheet group 22, reflection member 36 and chassis 24 are integrated and the bezel 27 is further covered by a front cabinet 27.
In the display apparatus described above, the buffer member 246 presses the back surface of the optical sheet group 22 through the reflection member 36, which does not restrict the positional shift of the optical sheet group 22 caused by slow expansion and contraction thereof due to changes in temperature or humidity in the environment of usage, while restricting the movement of each optical sheet in the optical sheet group 22 by the mutual friction resistance between optical sheets in the optical sheet group 22 for abrupt and frequent movements such as vibration or impact during transportation of the display apparatus. Therefore, degrading of image quality can be prevented, which may be caused by fine powder-like dust generated due to mutual friction between optical sheets and remaining in the light path or moving to an unspecified portion in the light path.